An appeals court hit the “pause” button on the recording industry’s battle against music-swappers yesterday, saying that Internet providers aren’t required to divulge the identities of their subscribers.

The Recording Industry Association of America had served about 4,000 subpoenas last summer, asking online companies to give them the names of people it believed were illegally trading songs. The RIAA sued nearly 300 of those users for copyright infringement.

After a prolonged court battle, the U.S. Court of Appeals for the District of Columbia ruled in favor of one of those Internet providers, Verizon, saying it was a “mere conduit” that did not need to comply with the RIAA’s subpoenas.

Sara Deutsch, Verizon’s counsel, said the company already had complied with about 400 requests because of the ruling by a lower court. She said those users did not have a legal appeal based on yesterday’s decision; “that cat’s out of the bag,” she said.

But she added that the ruling did stop recent requests by the RIAA for “thousands” of additional names.

Though the RIAA’s tactics were controversial, with the group targeting everyone from minors to low-income families, its executives said the lawsuits had a chilling effect on copyright infringement.

Some Internet surveys bear that out. Hitwise, which tracks traffic online, says visitors to Kazaa, the No. 1 file-sharing program, is off by 11 percent this month alone. Traffic to legal music stores such as iTunes has increased.